The present invention relates generally to mixing apparatus for producing dry mixtures and, more particularly, to such apparatus for mixing together such mineral, organic and/or plastic materials as dry mortar, concrete, feedstuffs, fertilizers, foodstuffs and the like. The mixing apparatus in a preferred embodiment includes a metering system, a control system and a transfer device to permit the mixed materials to be transported to and located on transportation vehicles.
Mixing machines of the type adapted for use in mixing dry ingredients are well known in the art particularly for use in mixing installations for mixing ready mortar. Such machines include a storage container in the finished material zone thereof. These finished material storage containers or silos must be provided within such installation for each kind of mortar which is to be loaded loose. The use of such silos enables various products to be mixed in succession, each of them being stored in intermediate storage zones in such finished material silos. As a rule, in such installations, associated metering, mixing and transfer devices must be cleaned between each change of product. Intermediate storage in silos means that extra machines must be provided in the zones of the silos. For example, an elevator may be required for raising or lowering the components, and conveying means such as, for example, a conveying screw or the like, extending from each silo to a transfer device may be required for the loading of vehicles.
In the dry mixing of building materials, particularly plasters and mortars, intermediate storage in silos has the considerable disadvantage of increasing the risk of separation since each time the materials being mixed are refilled, the constituent parts of the material, which have various grain sizes, may become separated. Furthermore, each of such intermediate storage containers requires measuring or indicating devices for precisely determining the particular quantity to be loaded, indepedent of the preceding production of the mixture.